Industrial textiles intended for continuous process and conveying applications, such as filtration, papermaking and the like, are frequently made in lengths of more than 100 ft. (33 m) and are often joined on the machine for which they are intended. The seam is a critical fabric component, and its properties should ideally be as continuous with the fabric as possible. That is to say, the seam should not introduce a discontinuity into the fabric once it is closed and the textile is rendered endless. The seam should also be easily closable by the machine operators during installation, and should be of high strength so that fabric integrity is optimized. Over the years, a great variety of seam constructions have been developed which meet these requirements to varying degrees. In the past, the vast majority of industrial textiles used for papermaking and filtration have been either wholly or partially woven structures, and the seams for these fabrics were typically prepared as extensions of the textile body. Pin type seams in particular have been found to offer various advantages in terms of maintaining fabric properties, and minimizing discontinuity, while providing a high strength join which is simple to close during installation.
With more recent advances in polymer structures and engineering, it has now become feasible to produce wholly nonwoven industrial textiles for filtration applications. These nonwoven fabrics can be formed from yarn arrays or similar arrangements of discrete fibers or, more recently, from polymer films. For example, it has been proposed in WO 2011/069259 (Manninen) to assemble industrial textiles from one or more layers of film which has been selectively slit and embossed so as to provide permeability and integrity. The film fabric disclosed in the '259 application can be joined with either a seaming element such as is described in WO 2010/121360, or a hinge type seam as disclosed by Lacroix et al. WO 2011/069258. While both of these seam constructions may be suitable for use in a variety of situations, a need still exists for a seam structure which is of high strength, maintains continuity with respect to fabric properties and is easily joined on the machine for which the fabric is intended. Ideally, such a seam construction should also be applicable to both woven and nonwoven textiles. The seaming elements of the present invention address these needs in a simple, elegant manner.
It is known to provide for seaming of fabrics by using punched, notched or similarly serrated openings between which are located joining loops or analogous arrangements. For example, FR 929951 (Nivoix) discloses a notched, U-shaped hinge seam component comprised of metal or nylon for attachment to a transmission belt so as to render it endless; and DE 4314356 (Melies) discloses a pressed film connection to connect the ends of rotating pressed films used to feed workpieces into presses, a plurality of mutually engaging flaps being created at each of the opposing ends of the belt, to receive a connecting rod to join the ends.
GB 1 266 719 (Wilson) describes a heat-shrinkable closure sleeve, constructed from a notched polymeric material having a row of apertures along parallel opposing edges, the apertures of one edge being staggered in relation to those in the opposing edge. The sheet is folded along each row of apertures and then bonded to provide a plurality of loops capable of receiving a connecting member.
U.S. Pat. No. 2,005,979 (Milnes) discloses a dryer fabric or felt which is rendered endless by cutting interfitting loops from the opposing fabric ends by first folding the ends back upon themselves, and then cutting out notches to form the loops, the opposing ends being joined together by means of a retaining key, or pintle. U.S. Pat. No. 3,309,790 (MacBean) discloses a similar seam construction to that of Milnes except that the key, or pintle, is perforated to maintain porosity (permeability) across the width of the fabric at the seam, and the notches and projections may be coated with a plastic material to bond the folded over portions.
U.S. Pat. No. 3,323,226 (Beaumont) discloses a papermaker's dryer fabric formed from a plurality of rectangular perforated polymeric sheets of film which are joined together by overlapping the sheets and ultrasonically welding them. The fabric may be seamed by folding back the ends of the fabric, stitching them in place, and then forming notches across the width of the belt. The resulting loops and notches can be brought together and interleaved, and a rod or pintle inserted through the loops to create an endless construction.
U.S. Pat. No. 4,911,683 (Legge) discloses a nonwoven fabric construction including one or more layers of batt material in which the ends to be joined may be entirely devoid of MD oriented yarns, the fabric ends being folded and subsequently notched to form a series of projections which can be intermeshed to form a seam.
U.S. 2008/0295306 (Despault) discloses a seam for a papermakers fabric comprised of intermeshing indentations and land areas located at each of the opposing ends of the fabric. The land areas are shaped to intermesh with the indentations at the second opposing end and then joined using a pintle.